SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b78a695257e66aa9ef551e0a3e0103f95c45c313a9e6264eac510c87e2f89918' 
  AND token = 'zvzNNBsEbua/mXkmbyvRJFfMS6IiZ3mFsKxwMTlB+U8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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