SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dff6f5fe0e807f210944e982f9c1811ad239dc7fb8cf420427513369933a04c' 
  AND token = 'eFkbc9/NKWG8iPOwCkInSIjZVwrGbY+AZN1HdGsaKSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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