SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a78fdde4941267e13c9231873ec9635ad28a4e180c0625f7169820654e425c0' 
  AND token = 'tKqGr/kko6FuMfMu2ITzkxdpbCjNKGvwybf7+5GqVB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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