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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ad8a021d0d5b997385c8915eda4a967cf1a8bcf8485677584fe29e7a679f5a3' 
  AND token = 'gVX/Cs0tGqL5CeQ/Fb+rxJDbDAHiA2D2DRhqOj+fdek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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