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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a31bedbfe2246b9e1272d8e6ece5cd726230f2eb3410f4fbb3559f8f9ba89579' 
  AND token = 'CZCDTRaJrQvrfIHimhTWYQ+sWImoMkTe9jtjVCoLLb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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