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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a9860a6ebeb53d4a8219d8a7af3e80f6e85eaf3889bb7f0235a2f79b8ef0279b' 
  AND token = 'fNmYpaCr9Lf8BLdZSwdaxthkiNxHjlMck0ezvVo26C8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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