SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c346b551e045a4a82a71e725272f29636c82fd2e81b59d45c6c6917bb1a1612f' 
  AND token = 'D7WfTMgezpl0aaH/P5vzHVortVjjJCx1ZcX8mJq3O6Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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