SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f44f8769eca483f4d1a5c0a0d06b440f8da9acacd65080f48beabbece5d3fc56' 
  AND token = 'T8AEXPJvQqYz9LiLKUpBtoygusLdPuqc2uISoTCqHYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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