SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f08048017d7c21b0768486f738bb194f9e123cf9c9b91974d9d5e51e986694a9' 
  AND token = 'q4A1NiUGU4vyhlbAiZrJzV4GSjWV3+3CorLZd8/cur4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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