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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '2796e13446f9b85b5d5b27dd94a92d9624dd02d5b5a48a5ec2f4635e0cc6ce20' 
  AND token = 'u/B+PndQm8oMWPCdaRFwV1//0X21qHMOz3iNiNg0iRU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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