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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf38af5f9b86bfd5a08c3cfc1acb23310793389d3daa0c3c04155549a1601b46' 
  AND token = 'MnmF/aXp2lvTsHg/0/aUH+gJYYc1tr4IoQ0A0bfUT4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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