SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8e199aec4bebd64b984da7f1d06a59037593bd9938edf038d01ca766db182f2' 
  AND token = 'onMBLjtFrjmHyeZeXsigjrZjBoXkg22cBb7vOU4OWik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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