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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4a1c9770001b3cb7f14763ec3fbfe4a16d55806e7f86dc7d95eb7e0012d0686' 
  AND token = 'r0QQi5nuR8Cus9QNrs+fyEe7B9FAJExs3zvMSDNhk6g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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