SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e27ed62368686b2c5d3661a2a01548e81dd9843f628d704198e6e053e514f01' 
  AND token = '6p4nL1Sqjhjl+12pL4VmY7SVv/xWDIFSJ+zwOVVPOk0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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