SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d933791d6e84a0f5ee8313447139faa375bf41e436c5b1501ef52d49f387460' 
  AND token = 'nPUjf8M5uFsb2L8gW6koQWYJj4gaYixouYWfYBjQFQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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