SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4214c14db72b0d6721c671bc4432ffc1927e84e2ec474b009d3f269a74931722' 
  AND token = 'fDt134LxfTnGJb92xNUD1sBDGFccYZ4Zc8WanTcok60=' 
  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"
    }
  }
}