SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd29dbdbee4b9471fac92634de1c6c9a93a753141b9303b3d0581da88b14a1c0d' 
  AND token = 'nsdmRK+iuivhN+AU8Hgl9oXfR2wmPAEpz5sGN4DpbZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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