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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5bd6ccb205a48c16ac8ab9304f3165605575411c6d5f691c48b6e4d6ede0f300' 
  AND token = 'dYN5oZjWtEJwuz3Z0t48tsJGSS9iJcAlMV0QCz1wmuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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