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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7b3b9c9cbaf4ead782f70dc17c75e9d3d745fcdfe1c0bc2fb46a61d46a9713c' 
  AND token = 'pCpqZEwBPiCzPnR42h1UI3iLM5Av8dT81/zKoDFWy3I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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