SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c21616813573775171290910d1ef85b1508e79804cbd74c2945f3e7220428b7' 
  AND token = 'b6labsLJ89kcjpVgkm3JGUluviXK6HzhoaFk+BmcguI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00105

JSON explain

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