SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6bb20e52d869bddc88a4d4afb1261fe8810ace87173da6bea3788d2a566d836' 
  AND token = 'qkdyKbjR2VIBlBEgDpmyTkd/OuizTthcJZH0GbTy7IY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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