SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a69a27888a3b59f9e42c071eeaf9237e20be560d6f953499415652f8e32c0d90' 
  AND token = '/uI2vzI/r6JE1EdDYDAGqHFWD0G8VVAyUjtwdp4Th0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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