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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c976e14d41bedd725d72c0dcd8bd1d6a5c4f22687c035f6817b56a1aa3fd31ff' 
  AND token = 'x/gPz9BWKnQCi1/cFnmuEMhyTOFiofDYn0OXtjTMWN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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