SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91a687e36c135a7d1b833a18eff8f4cf12f78849dbe2e824f7021ea5bfed74b6' 
  AND token = 'rr91x/kuq8AOMALBChUlSg6kRm0IfGPsKMY7w8mkwJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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