SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71a5ec3f2d94f3a3687286ef4620cdac88681b634a84769ed15efb6b96cfff09' 
  AND token = '/fwZmHPZ3Y+ws0uDPXl9r1qePs6pBHtFoSUKvUgSPQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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