SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6705679ef8b69c7115a82232afa67cc518b3226337cc5aec51b8dbadefe4b7c' 
  AND token = 'qmaxBrXDPukQZYwODSka9Eb04+641ma4hzxZCLuzn3Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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