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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd1cf302f15809a2479726cf86ef4c0a7fd24e9ff7bbd3c828f22c03a49b3d4b6' 
  AND token = 'n6QzV2lM3D+6BfuCTQEtqOTZkDqNpNrN9ZX7S9yWq/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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