SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d38512016af5809974021f2db1b9d949605fa1ccbff83cfb060ef3ca73a1dea' 
  AND token = 'E/y2EOFfTJKb9rP4e4l2R/YNtDt2t762FcFQNAU6mjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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