SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8388e9195907d0a598207acd087d382ecc6d8a035f61f5b09c9a99ac063bee1e' 
  AND token = 'MZ7qJMiFqZH7ZFBJP8ugTMwEsbtys+cpNgeoGuEarMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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