SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54b6e61bbd07d74b82a1f47b5981a1f1f10d7c86516cdf7f437e7171a36fe7bc' 
  AND token = '8aR6/grRBTrTG0gSJCg33pxWw0/f6R9QbRxvwf7Ncao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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