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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd9b19ad68fb7eb29b425873dc518e105f47e987ab5527c21f49064ad9de85d3' 
  AND token = '/IXEAPJ3bHWRAdcY96lMEavWz/T9CE6zqwb9hgPn7Ng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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