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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'dfd0cd536a480362b045eb0dbf00d0f6e3aeb47b395bf3f2e5c4b50c3bd81ce2' 
  AND token = '3GcAZBcGo2lGdzwN2zWMI7v/YeTZEtKEtiydPXSqPK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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