SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a900245093886def74c57d3c58af7465e478596632e403dca05eb9481c72fb1' 
  AND token = 'kvpkvDsgEJzvp3JlAznUjG0wWLxmfV4aGAzh0jPzgTU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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