SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b00417492813eb3c0105b99668c99c8c1221352218da1dedc41a8ab8822cc86' 
  AND token = 'clOtWTd66wlInZGnEdnyqoPzYDiiYhqbTQhrIEMDLH4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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