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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b6b0850b925441baf96d0d6637fb81b8568f30a695749bff3aa7f78ab6152e02' 
  AND token = 'CG8rkDXzXwLl0zJ0A7ck5BsFGdWhwYAc6eI/Wo5ri94=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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