SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '837b2271424c53e68e1d458892f2a40f4909fac613fcde855b791329342fe0c0' 
  AND token = 'K/+QoOrqlSxH0dk1EJHnkVyLFPeqgAVvBLSyRfeQXDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}