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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fd11c1fa38ea1f5f91f389e87e009c25b8b283a54c71d25ab75df9dc600fbe68' 
  AND token = 'n2/8AfMVd+yKw6oqW9LK+ek2c8UvvuAmneiL9/nM2v0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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