SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b4355ccdd101157154016ac7cb2958924149d92993c573f345680608dfd6543' 
  AND token = 'fDaRt1B64OkWU0BPQB6/MBk5jNNF2/m2PCQ2Ru/rD64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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