SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d22b92fd725b1358714fc2706d61a9737cba247e15baaab19017e7cecb9af19' 
  AND token = '3rN/ErU/77PYByMX9pwk3dbJQXSxS3SBdmgRHlollBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}