SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bd15cbb1d0dc069a009d2c5c7bc509164a9422993b31023871894d787364b38' 
  AND token = 'h7sp6ULYsiXqKM5sUvkRoJWvPmg+rh0GEUuBPCzzIMo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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