SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c4e41f6dddd3be0b856ae42ed19982ec59ec852048fe8a0fa53e71144ce015b' 
  AND token = '1vStcjU1VUjTIzQPkZkfLs5RwdDvbwrvgQvQ1/ZKafo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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