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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fed0f0f64999ea67cc36740c6408708b08ebf91e9df5d09d7e937421c9336ea' 
  AND token = '3QjuSxe7RoFvfF0mUeGZ3BzQo5qW8XT/ZbdLDnUCgkE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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