SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40f3b86f4984c9e6399dceb97a355383d487f21edbf15546b63bfa3c2f42872f' 
  AND token = 'S2F+3j6RTFErnyhkZybrS0gIt9bLzOBdP/XsJ/8+PBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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