SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '284f43b3416bfa356c0b6a686e29a2745d7b20f6c85199ad9176385c94144e2b' 
  AND token = '5NtSzdUdDKE2pCD0GeVDtkfgDXcGOsma9tZMjaqzbBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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