SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e50d3d218a0dafef7a46dee23d3547720feafa4a59786c59997728dbfdd0be8d' 
  AND token = 'wppn1GBiqP+4UB2v5t2iHhKkJ6eIU/UXqKP4zkBRPHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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