SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '018874f927b2fc5bd63345bd62bc9377549aac13a78a2d5df3dfbc5d359aeba2' 
  AND token = 'W0BLR5ZqXaZUiFI/6ZVPAXknTbUQ/Pgd47Jhj+kAPhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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