SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7cb49244fe0c52dec20438e84c8b704521ee4ee725ff85cdedbf9c18df26c6a' 
  AND token = 'V5EEZCgEEMU8UQS8EuJBiJs9NMXbq6ZkHJWYfNQujR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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