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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4a7f20f2d85361c263dbe4b21aec88d0ad01fd5b8a85ad4338c3f4f68d69e60' 
  AND token = 'jjrSji3fZGy1M/THWq8OnVJiLPMGkCr5Y1XFl6j5VXo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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