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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b0d8c3876aa7f7de2497ae4f141b190d1a1f3d0f6b0c9b352a08884e122a508' 
  AND token = 'RbZhfL2PFTMpEdJ7QmTOKiZtB7dQ0LmLjHZx0pSBn24=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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