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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f40c100429797e30c006b3c5804a31ed3224f148c3904a49b3d1b3964a65c5cf' 
  AND token = 'AQ8tqKvoKg3xJjVTB5MFf7wjkx9L0TbpzVkcFc4DZ5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}