SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2f7a4a1659e8973cb36d1c2c389c0a1520bbe9cd979ecc5b74e6adcc3c9c267' 
  AND token = 'kDVbexm60zT+9vywbWunDd0Taye7rSgNBRniIM+KdR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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