SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81680d5c7df2d5e696908748d8344a9f343fb3e36b2347b1af90c19dd867a0bf' 
  AND token = 'MbxAAVh6vSRjTgl7Paq1MP9wxZFDyZGl/nIKeT/OB3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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