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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7f243d11d8fd13688b690320e5aefbfc1b2da665eeb947c945d7aa1157a54bc6' 
  AND token = 'jtslvwSVi7tE6eOCamD8FSCVItC4oTQ26wRCse26q5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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