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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ddaac91f8d6566df9aff8135fe2f29b0185d4b0d7f9202f7bef1d659afd73e36' 
  AND token = 'HjtA1MVCsK9PHCocGd6TbWwoNX9ea4muCs9bLN4kSIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}