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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b7aed546ce4af37110ad357ef845db818c72443d7d7084fe3c441d890235b1e5' 
  AND token = 'iQTryKeJFgUO2ABo1saxrFgSXZki/miS+NiIXH2Krpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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