SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '908b3eedc4f526c84488ad37c63b6420af83c489e51026d58a7c597af18fcdf1' 
  AND token = 'z0DH1e6zq+Ru6rUtUIhzDfAJqcZPAOSBttvjDwaolWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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