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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c12920be12e6f75c9c4950c4f039c6f2dbce56cb99e7838c9bec901a8a80bb09' 
  AND token = 'eC2r8Ng/RaZBMCv0PyatTcY6eIQD+yiHpdEF3I3DIrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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