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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3b7ba386581d18812a03febac3fbfe948a1c6f19e4386e2203fa4467cb30c8e' 
  AND token = 'VAoY/fyXoGOyOmrZ8X/TkhPlw0piSCn+Is3BbS/hxVk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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