SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f3607d239f1f765f2c900f35968c8783b1437fcc54455793955d5241029b071' 
  AND token = 'qypVPutEQLSMutPgzR+sCZYLlw/KLhhzXtgF2OhEsHU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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