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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4f9ea123a9473d9b7536560d65e10678bde45cc8fc2861bc75717c16a4eab37' 
  AND token = 'h6NpKimM23rHYuS+EgRp1woWTUmSt+vYjf/Mfm7D7Kk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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