SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51bf316634d4244393abef4ce4bb353a9f53b2baea18247e9b6e28c86272f010' 
  AND token = 'dRFrKnFHDgWNqcL3SPTF3nftkj71SydspWQKXPHkdZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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