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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c1fc5ca68c4135044ec2e9ff0eccbf46d29d28f59d25be5f9de2b963dc018490' 
  AND token = 'jDitdg3PHkI4rwD7GMqg9v5k7v0acMYcKowdtI2gCtQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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