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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7756efb867dc1c9b7c5a5dceac9294615623c2c9be95396a1733c9544c5cbf3' 
  AND token = '1UHOiC3ClIY9aDrEKvG8H6Y0K6lLb1jdE892ZRn0Px0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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