SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fdd275888864d0bca7daf943a755d539d6b8440b840da98ce011bc27dc6b0ba4' 
  AND token = '2oosUHLJz1UfcAfpNAHvssmsvXGeN9xsvfuKP6W92vU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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