SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c5170535490aea62acc26330b09a101a756801fa96b9520e012b6cbdd3550db' 
  AND token = 'stL0IY1N2zpUg4BrZFhuC/mUT1PeZsa2rq/cJL6cCG0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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