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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e21da8bd22acf677499210e0a1fcfa9be7a5405e1304ef90f437c48abc435698' 
  AND token = '46dau6TManaRn0/ev0iCpjL3btV2JPJWhIzc6K2RWpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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