SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1f856092a8198248e8f82d313955da179caf75d6a76d65d2f9e26e5f03cf9b0' 
  AND token = 'jBXsBB4MAA2Zq5NhaEuFI1RMEwEnp4ZpbC3dEGLuUts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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