SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bc859224281cce8646c94568cd0f0a929f23ab15ce32ef6f8442423ec38348a' 
  AND token = 'Qga4fllYHWib+890nM6+7vH2gJgBvUgwV39NUInxamI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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