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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f3e8b3cc34b38d10dfc9bae174737e9c2f94fab137a913d1f7a3a4b30b2441b6' 
  AND token = 'f3rLpLX9ucvCLJiA10PUwTDCNRKioJ/9tyutFn9jvXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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