SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52c919c2927b9cc8a42a6504352b73c75ce0ded32b5be0e35124ee3d1cecab6e' 
  AND token = 'kM5xQujJ+Lk0E6PrSvhZMV2ZGzRubikXMsynUpbOMo0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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