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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '793a5fab4b48c928f7f55cc943f648a45c51fa41a7faff7166ba1b0cf37be2f5' 
  AND token = 'NoWH/r3flkRVZjcOnBFgzw6F75s+SSPvRMu4nL3CSeM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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