SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a103bfa5d3428b936315216fb613376d7899df710ee4b0a55dfe4def8ea94c0f' 
  AND token = '7mWXGSz6qAkIBkzn9k7bzbbSGCxBX4d6008z54FGg4o=' 
  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"
    }
  }
}