SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53186d76763cbe29a09aab855f51a0c28581a2dd52262759588265f984d6a1c5' 
  AND token = 'wG8pN08stjDTb8HIoaAm2pqv3t9+WTn9+wAcU6BX5Qw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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