SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e87be9cc24acca4ad0d774ac0a71c8f810d4089034ca22a2dd8a951ab49b5866' 
  AND token = '+pVAYfizo9pmkiv0FSVCIBtwinrxS7AMMeB2/qUq2G0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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