SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3a616ea11853bfa78c820a43f42a7260bc4c8deda8dfa60f6949714b23c3611' 
  AND token = 'fJDY28eIMecIhzqaV4s8mEEls6ugIVANfp6tvMBVQmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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