SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de2774109d4783a995dcddfd0e028bc2796fe14158d56351fca4f2421d9c1638' 
  AND token = 'vkzzCIMdjcKDs6FdKbVz2MMxaUZO29eILBjvyDUyVME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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