SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd51ae7ade5bc0ce8169f69c374be3339eb26134be3e1774220bc738376c5bc55' 
  AND token = 'MhJBJRiLApsu8UqnuFqQE3rzaL3DHHrySg4cBWiX/FU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}