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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f98b1f9e87bf84a0503fde82ab0f9393885529fb51a4708509e3b53031b85ef4' 
  AND token = '4rPcBgrKSlvmWAL9ilirJYZ/Jydh1AiOtwgmvLHwhKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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