SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e3da3dfdc531e402f7a40c80aa6ed37989139e99af7cbb65de74e751c0a0050' 
  AND token = 'H2GzNHs8NTFqbVpvusH6Spmj56pmxjJxSVDUjOnndsc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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