SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b1bbb02a31762d2ba9d78fa65664cc24961012fb5a8460f501fab45027db528' 
  AND token = 'SiLS+OSTJW49FsuTWcD3lu/NPjlKwUmsvfNjQfDgA5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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