SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '900c3e040246bed7131bedfd00d80a8f6688de087a880467582e3809c1a8ae9c' 
  AND token = 'FIz//i1b+GfFb/prmuSRpuC6UloaBK53kfWmXR/QfGc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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