SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd494f7274428823a3910da68b4f13bf143b0b3c5f862744e3493ba4e1832f6df' 
  AND token = 'epJGZ5ua6pYcPBVUBWSvPv6JqQhRMn/P3WfFDr413Pg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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