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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1c52e301c3ca04d76abef9c3fc88618a40c76dbb7e1172b8eb46b4fb5d11d3c' 
  AND token = 'mZhvv66jnkBlMFwFNqp7npoFvOo5Sx/RV08m7OfxlcA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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