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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'afd5d2b9fc19697a70a45474d2424d23da4128dc3c3a6d8ba370925e6a3429e9' 
  AND token = 't+cnVMmVcmVClAN2AkGXXfZ1De2IhZ1LOxi9uSfHllg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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