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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd89594d87239b320d7f23445b323be01028372745bf8511cf10e4feed3cbbc38' 
  AND token = '1suiz7Al07t9XgeLNj8xRBme09icfvqCOAimXqfZCpA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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