SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b6d4a7a779bc6cedfdaaaeb99d15e588bde99c4454649a5593fe343f640953a' 
  AND token = '+iEvY4RBbds80nZA4JtYcdMsfW2JzM+oH7fVscSVCl0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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