SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29e70942c27b38ffbb92dc9594947c265214e2e0fd188aba4daf5798e61664ce' 
  AND token = 'smNH51RvBHxwAnS2ICSJCW8lbCXer08hUgUJZuDVNFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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