SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b770f1b5987c0b5b41cedff187e1dfa635a7300b66062189905a8c25278f6761' 
  AND token = 'WRPnajFO+QE0usezZQDJCVNysqJ4tr1K+VyRE3g4MMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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