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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5b912ddaaa56047a6f0ca7d08da2a6bcfae4b665a2fc6be651cc4ee23ccb46c' 
  AND token = 'TZ8nBLm6V+KIzEEezW2EsMlnpD4/3JvglG1Donpg0oE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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